Fix bug with execution of naked multiline strings.

The actual bug fix was a trivial one-line change, made here.  The rest
of the commits in this series improve our testing machinery and clean
up related code.

The actual fix was just calling the run_source instead of the run_code
method, which should only be called with compiled code objects.

IPython/core/tests/test_interactiveshell.py

@@ -0,0 +1,37 b''
+"""Tests for the key interactiveshell module.
+
+Historically the main classes in interactiveshell have been under-tested.  This
+module should grow as many single-method tests as possible to trap many of the
+recurring bugs we seem to encounter with high-level interaction.
+
+Authors
+-------
+* Fernando Perez
+"""
+#-----------------------------------------------------------------------------
+#  Copyright (C) 2011  The IPython Development Team
+#
+#  Distributed under the terms of the BSD License.  The full license is in
+#  the file COPYING, distributed as part of this software.
+#-----------------------------------------------------------------------------
+
+#-----------------------------------------------------------------------------
+# Imports
+#-----------------------------------------------------------------------------
+# stdlib
+import unittest
+
+#-----------------------------------------------------------------------------
+# Tests
+#-----------------------------------------------------------------------------
+
+class InteractiveShellTestCase(unittest.TestCase):
+    def test_naked_string_cells(self):
+        """Test that cells with only naked strings are fully executed"""
+        ip = get_ipython()
+        # First, single-line inputs
+        ip.run_cell('"a"\n')
+        self.assertEquals(ip.user_ns['_'], 'a')
+        # And also multi-line cells
+        ip.run_cell('"""a\nb"""\n')
+        self.assertEquals(ip.user_ns['_'], 'a\nb')

IPython/core/interactiveshell.py

@@ -2174,8 +2174,11 b' class InteractiveShell(Configurable, Magic):'
         if len(block.splitlines()) <= 1:
             out = self.run_single_line(block)
         else:
-            out = self.run_code(block)
-            #out = self.run_source(block)
+            # Call run_source, which correctly compiles the input cell.
+            # run_code must only be called when we know we have a code object,
+            # as it does a naked exec and the compilation mode may not be what
+            # we wanted.
+            out = self.run_source(block)
         return out
 
     def run_single_line(self, line):